The intraluminal shunt of the present invention relates to a device to be inserted within a blood vessel to allow blood flow during an operation, such as a coronary bypass procedure, wherein the procedure does not involve a heart/lung machine. A relatively common operation in which anastomosis is employed is a coronary artery bypass operation in which blood is routed about a blocked portion of a coronary artery to restore and insure adequate blood supply to the heart muscle. In a conventional heart bypass operation, a short segment of a vein taken from another part of the patient's body is used, with one end of this vein connected to the aorta and the opposite end connected to the blocked coronary artery beyond the blockage. The connection of this vein between the aorta and the coronary artery serves as a bypass around the blockage.
Standard operative technique for providing a coronary artery bypass comprises first clamping off the aorta to occlude blood flow to all the coronary arteries. The bypass connection is then made by suturing the vein in place. Many times multiple bypasses are required and, as a result, it may be necessary for the aorta to be clamped off for an extended period of time during which there is no blood supply to the muscle tissue of the heart or myocardium. The prolonged suspension of blood supply to the heart can result in life threatening infarcts temporarily harming the heart muscle.
To overcome this problem, the vast majority of coronary artery bypass grafting procedures are performed with the assistance of cardiopulmonary bypass (CPB) and cardiac standstill. To stop the heart is traumatic to the patient and may precipitate undesirable ischemic conditions for the patient both during and after completion of the operation. However, an advantage of the use of a heart/lung machine with the attendant stoppage of the beating of the heart for the surgeon is that the heart is motionless and blood-filled, making it technically easier to fashion delicate sutured connections (anastomosis) between the coronary sutures and vein grafts. Thus, the surgery is less stressful and the results are consistent and reproducible from one operation to the next.
In the last decade, there has been progress made in performing bypass grafting without stopping the heart. To accomplish this, a segment of the blocked artery is temporarily occluded and a bypass graft is inserted. However, in these areas, a condition occurs in the patient known as ischemia; i.e., there is a lack of blood in that region from surgical control of the target vessel. This can cause strain on the heart, with changes in the EKG, dangerous rhythm disturbances, or stoppage of the heart beat. Between 15 and 30% of coronary bypass operations done on the beating heart are associated with EKG changes resembling a heart attack. Fortunately, nearly all of these changes are temporary and resolve upon restoration of blood flow in the target vessel. Just the same, there is constant pressure on the surgeon to finish quickly and get the bypass graft open as quickly as possible.
To safely perform coronary bypass grafting without the need to completely arrest the heart, a shunt device has been designed; the shunt providing blood to the starving heart muscle while the surgeon carefully and cautiously constructs the new bypass. The shunt design presented here has many unique features which provide major advantages to the surgeon during off-pump coronary grafting.